Can't install Osteotomy Planner extension

Operating system: Windows 10 19042
Slicer version: 4.11.20200930
Expected behavior: Find extension in Extension Manager
Actual behavior: Extension Manager does not show Osteotomy Planner extension

I think Dynamic Modeler that comes by default in recent releases of 3D Slicer pretty much do everything that the osteotomy planner does

@Sam_Horvath is working on reviving the Osteotomy Planner extension, so that it keep high-level features of the planner module but uses Dynamic Modeler module internally. Until this rework is completed (no ETA, as it is a low priority task), Dynamic Modeler module can be used.